Questions on roof repair ( adding a 2nd layer of shingles )
First off let me just say that normally I would just tear off the first layer so I'm able to inspect the roof better and replace anything that might be an issue. The problem is I live 20mins from the Pacific ocean in WA State and it's going to be difficult to get enough good days to do a complete tear off.
Since I'm doing this myself I think adding the second layer for now will have to do. I just acquired this home due to foreclosure and it is apparent there are a few small leaks that recently started so I'm trying to minimize anymore damage to the plaster, etc.
I have experience doing many different home repairs but this will be my first roof repair. What are some of the things I want to make sure I do when adding a second layer? Is it necessary to also add a second layer of "tar paper"?
The home is a 1916 craftsman. It has what I would guess a 10/12 pitched roof so it should be interesting.
Any advise I could get would be appreciated.